When I was twelve, I was interviewed by a doctoral candidate in education and asked what I wanted to be when I grew up. I said that I either wanted to be a philosopher or a clown, and I understood then, I think, that much depended on whether or not I found the world worth philosophizing about, and what the price of seriousness might be.
Contentment is wanting what you have. Ambition is wanting what another has. Progress comes from wanting what nobody has.